The present invention relates to a floor-heating method and radiating pipe for use in floor heating.
In conventional floor-heating methods and floor-heating devices, a heated thermal medium is circulated through long, thin seamless pipes installed under a floor. Alternatively, a powered heating cable is installed under a floor. In the system involving circulation of a heating medium, a circulation path for the heating medium is disposed under the floor. The circulation path comprises seamless pipes made from a material having good thermal conductivity. The pipes are installed under the floor using embedding panels. A boiler is disposed outside the circulation path in order to heat the heating medium in the seamless pipes. A pump is also disposed in the circulation path to force the heating medium to circulate. In the system involving heating cables, it is necessary to form the floor surface using concrete in order to fix the heating cable.
However, in the system involving circulation of a heating medium, the temperature of the heated medium gradually decreases as it circulates in the seamless pipes. Temperature at the portion of the floor corresponding to the front half of the circulation path (near the boiler) will be high. However, the temperature of the floor corresponding to the rear half (away from the boiler) will not rise. Thus, it is not possible to provide uniform heating for the entire floor.
Also, since a pump is used to circulate the heating medium inside the seamless pipes, a large pump may be required if the circulation path is long or if the heating medium is a viscous material. The use of a smaller pump will put an excessive load on the pump, requiring large expenditures for maintenance.
Furthermore, since a boiler is used to heat the heating medium, the boiler will generally heat an entire tank containing the heating medium. Thus, the boiler loses a significant amount of thermal energy in heating the portion of the heating medium that will not be circulating. Also, heat is dissipated in the process of medium reaching the circulation path, and this results in heat loss that increases the operation costs of the system.
The seamless pipes installed under the floor will generally be made of copper. These pipes must be bent manually to form the circulation path. Thus, an experienced operator is required in installing the seamless pipes, and the installation will also be time consuming. This results in the entire installation of the floor-heating system being slow and expensive.
In systems that use heating cables, the heat dissipated from the heating cable is not efficiently transferred to the floor surface for reasons that are not clearly understood. Since the floor cannot be heated to a desired temperature, it is difficult to have the system provide heating at the predicted temperature. If the voltage or the current going to the heating cable is increased in order to force the temperature higher, greater power consumption will make the operating costs extremely high. Furthermore, since the positionings of the heating cables have to be fixed in concrete, this system can only be used when the floor is laid with concrete, making this method impractical for general home use.
In response to these problems, the present applicant developed a floor-heating system that uses a two-layer pipe structure, as described in published Japanese patent application 7-121449. In this technology, two-layer pipe structures are installed parallel to each other. The inner space of the two-layer pipe structures are made continuous, and water or a heating medium is sealed in this inner space. A heating body is passed through the inner pipe of the two-layer pipe structure.
This technology allows relatively easier floor-heating installation. However, the amount of work required for installation is still significant, and the method is not suited for situations where installation must be performed in a short period of time, such as for remodelling. Also, since water or the like is sealed in the inner space of the two-layer pipe structures, there is a need for adequate water-tightness.